Lightning-arrester



(No Model.) 2 Sheets-Sheet 1. M. J. WIGHTMAN & H. LEMP.

LIGHTNINGARRESTER.

No. 363,567. Patented May 24. 1887.

@Vitwwoo 40. W QM (No Model.) 2 Sheets-Shae; 2. M. J. WIGHTMAN 8v H.LEMP.

LIGHTNING ARRESTER.

No.3 3,561 Patented-May 2.4, 1887.

UNITED STATES ATENT UFFICE.

MERLE J. XVIGHTMAN AND. HERMANN LEMP, OF HARTFORD, CONNECTICUT.

LlGHTNlNG-ARRESTER.

SPECIPICATTON forming part of Letters Patent No. 363,567, dated May 24,1887.

To all whom, it may concern:

Be it known that we, MERLE J. WienTMAN and HERMANN LEMP, citizens of theUnited States, residing at Hartford, in the county of Hartford and.State of Connecticut, have invented a new and usefulLightning-Arrester, of which the followingis such a full and exactdescription as will enable any person skilled in the art to which itappertains to make, con struct, and use the same.

Our invention relatesto devices which are designed to protectelectromagnetic apparatus from discharges oflightning,and which conveythe lightning-charge to ground before reaching the apparatus to beprotected.

Our invention consists in certain details, to be hereinafter described,and which will be specifically pointed out in the claims hereto annexed.

In the accompanying drawings, forming part of this specification, inwhich like letters of reference indicate the same parts in the threefigures of the drawings, Figure 1 shows aplau ofourinventi on Fig.2,aside elevation thereof, andFig. 3 a diagrammatic view of ourinvention for protecting a dynamo from discharges of lightning.

In Fig.' 3, D represents a dynamo machine, and Lthe main or externalcircuit thereof, in which circuit, and on each side of the dynamo, isplaced a rotatable spindle, s, hav: ing a screw-thread cut thereon.Contiguous to thisscrew-tln'eaded spindle is a'conducting -plate, 1),which is connected toground through the circuit of the electro-magnet M,which circuit isin electrical connection with the armature a, havingextending therefrom a conducting-arm, b, which makes contact with ametal plate, a, which is directly connected to the ground G.-

The construction of the lightning-arrester is shown in Figs. 1 and 2.The metal plate 19, as will be seen in these figures, is adjustable toand from the spindle s by means of screws 8'. Upon the standard uponwhich the spindle is mounted are binding-posts, to which the circuit tobe protected is connected. The plate 1) and the contact 0 are also eachprovided with a binding-post or screw for making the electricalconnection. The sharp points afforded by the screw-thread 011 thespindle 8 permit (No model.)

the lightningcharge to readily escape to the plate p and to ground, andthe rotatable feature of this spindle subserves the useful function ofbringing a fresh portion of the spin dle opposite the plate 1) after theportion previously opposite the plate has been burned out or destroyedby the discharge of the lightningcharge.

We make the elcctro'magnet M of low resistance and sluggish, so that itwill not act to break the circuit at the contact 0 until after thecharge is passed.

The object of breaking the circuit will be understood by reference toFig. 3, when it is known that after a discharge has taken place, and anarc has formed between the spindle s and the plate 1), there is atendency of the current from the dynamo to become short-circuited atthese points, thus depleting the external circuit of its current, inthis case having the tendency to pass from one terminal of the dynamo tothe other through the groundcireuit. It becomes necessary, therefore, tobreak this groundcircuit after the charge has passed, in order toobviate the above trouble. It will be noticed that the proximity of theplate 1) is such as not to allow the current normally flowing on theline to pass to ground, but that this tendency arises only after an arcis formed. The plate p is, however, arranged near enough to the spindleto allow the charge of the lightning to pass to ground.

We do not wish to limit ourselves to the exact construction shown, andreserve the right to embody our invention in any form of apparatus thatoperates upon the principle of our invention; but

What we desire to claim, and secure by Letters Patent, is

1. The combination, with an electric circuit, of alightning-arresterconsisting of a rotatable screw-threaded spindle in said circuit, an adjustable conducting-plate contiguous thereto, but separatedtherefrombyaspacaover which a lightning-charge may pass, a groundconnected with said plate, and an electro-magnet, its armature, andcontact-plate in the circuit of said ground, operating as and for thepur pose set forth.

2. A. lightningarrester consisting of a rotatable screw-threaded spindlein the circuit to a ground-circuit containing an electro-magnet,armature,aud contact therein, for the purr 5 pose specified.

In testimony whereof we have hereunto set our hands and seals, this 27thday of July, 1886, in the presence of the two subscribing witnesses;

MERLE J. WIGHTMAN. L. s. HERMANN LEMP. L. s.

Witnesses:

WM. E. SHEPARD, 0L0]? OFFREU.

